A few weeks ago, I noticed that a plant (some kind of fleabane) had a good colony of green aphids.
After a while, some of the green ones seemed to have made way for a new kind of reddish aphid, a strangely oval brownish thing. (confession: these "ant mummies" first showed up, like here, on a Fleabane plant. They also moved to the Goldenrod!)
Abby Cahill, an Invertebrate Biology Prof at Albion College, introduced to me the idea of Aphid Mummies and explained that they were caused by a wasp who lays her eggs in Green Aphids, which eggs eventually eat up the Aphid from the inside and then exit as adult Chalcidoid Wasps. These Mummies have a hole from which that wasp /these wasps had exited. I don't know what the pink stuff is coming out of the other end. Maybe the "skins" the wasps had been inside??
Another colony of green aphids sprang up on a Goldenrod plant. They were doing rather well. In picture 2 you see a healthy-looking group on July 28, one even giving birth. On July 29, I saw an ant that might have come along to nanny the aphids. That ant seemed to have a golden sphere attached to it.
The next day, July 30, although several stems of the same goldenrod had viable-looking aphid colonies, There were on this one strand some problems (picture 2). One of the aphids in picture 3 seems to have the same balloon-like thing as the ant in picture 3. And one of them seems to be shedding its green skin for one that looks suspiciously like an aphid mummy (click on the picture to see this one).
I asked Steven Wang, who is famous for always having a cogent explanation of things. He said that the Ant and the Aphid with the odd yellow swellings on their antennae and legs are probably suffering from protection that has evolved to protect the Goldenrod from insects such as Ants and Aphids. Apparently the hairs on the Goldenrod's stems may be producing a chemical that irritates the Insects' bodies and may eventually cause them to suffer from a buildup of fluid in their little bodies. I was shocked to be reminded that Nature has this side to it. It reminded me of what happens to people who get congestive heart failure. I have a very bad tendency to anthropomorphize, but doesn't it remind you of that people problem?
copyright Martha O'Kennon 2020